SANTA CLARA (CBS SF) — Talking about acing a test, San Francisco General Manager John Lynch’s 2019 draft picks have helped fueled the 49ers remarkable turnaround from a miserable 4-12 basement dweller last season to this year’s Super Bowl.

Certainly, quarterback Jimmy Garappolo’s return from knee injury and the addition of Dee Ford and Emmanuel Sanders has played a major role in the team’s amazing rise to the elite, but the draft that most NFL prognosticators gave Lynch and company a mere “B” rating for has jumped to the head of the class, particularly four of the first five selections.

Let’s do a quick review.

With its first five choices, the 49ers took Nick Bosa in the first round, Deebo Samuel in the second, Jalen Hurd in the third, Mitch Wishnowsky in the fourth and Dre Greenlaw in the fifth. While Hurd spent the year on injured reserve, the other four have been major contributors.

(l-r) Nick Bosa, Dre Greenlaw, Deebo Samuel (Ezra Shaw/Jamie Squire/Sean M. Haffey/Getty Images)

Bosa has blossomed into a fearsome pass rusher and steady, every down defensive end. His combination of speed, power and instinct is exceptional. He has been named the NFL’s Rookie of the Year by the Pro Football Writers of America after finishing the regular season with 47 tackles, 9 sacks, 1 interception and 1 forced fumble.

In the postseason, the rookie out of Ohio State has picked up three more sacks and constantly harassed Green Bay’s Aaron Rogers and Minnesota’s Kirk Cousins into several hurried errant throws.

The 49ers 4-12 record in 2018 earned the team the second pick in the 2019 NFL Draft, which they used to pick Bosa – one of just three 2019 draft picks to make the Pro Bowl as rookie.

“Everything happens for a reason, and you need to get good players in, some difference-makers, and Bosa has definitely been a difference-maker,” said 49ers coach Kyle Shanahan when asked to reflect on his prized rookie’s impact. “I’m very glad we have him. I don’t wish 4-12 on anybody, but after going through it, it was nice what it brought us.”

Samuel also has emerged as a potent dual offensive threat with his receiving ability and his punishing running style. He had 57 receptions during the regular season for 802 yards and 3 touchdowns. He also picked up 159 yards on 14 carries — a gaudy 11.3 yards per carry average — and scored three touchdowns.

With running back Tevin Coleman nursing an injured shoulder, Samuel’s rushing ability may be key for San Francisco in the Super Bowl against Kansas City.

His physical play has certainly impressed his head coach.

“They (tight end George Kittle and Samuel) are football players who play like men out there in terms of their physical,” Shanahan said. “They are not scared of the moment.

Wishnowsky, a rookie out of Utah and a native of Perth, Australia, has been a vital defense weapon all season long. He’s averaging 46.5 yards a punt, pinning opponents inside the 20-yard-line 23 times for a 44.2 percent average while only having 2 touchbacks.

And then there is Greenlaw. When starting linebacker Kwon Alexander went down with an injury in Game 6, Greenlaw stepped in and the 49ers defense never missed a beat. But it will be one pivotal play that will remain etched in 49ers fans hearts for years to come.

With time running out and San Francisco leading 26-21, Seattle marched to the 49ers 6 on the regular season’s final game. The NFC West crown and the league’s top seed hung in the balance.

On fourth-and-goal, Seattle tight end Jacob Hollister caught a pass underneath but was immediately knocked down by Greenlaw with less than 10 seconds remaining. Replay confirmed Hollister hit the ground inches before the ball reached the goal line, and the San Francisco’s celebration was on.

“I just knew that I had my foot on the goal line. I knew that they had to get into the end zone in order to win the game,” Greenlaw said after the game. “So I just made sure that my feet were on the goal line and just played lateral to downhill and just, made a tackle that my coaches and teammates would be proud of. Just happy with how the game ended and happy to be able to make the play.”

In the 49ers playoff win over Minnesota, the rookie came up big again with four tackles, three of them solo, and a forced fumble. For the regular season, Greenlaw ended up 62 solo tackles, 25 assists and an interception.